1. Field of the Invention
The present invention relates to a manufacturing method of an LED of a type of round concave cup with a flat bottom, which can be used in surface mounting light emitting diodes, point matrix light emitting diodes, seven sectional displaying light emitting diodes, LCD back light products, lights inner a car, braking lights, traffic lights, outdoor broadcast boards, etc.
2. Description of the Prior Art
With reference to FIG. 1, the schematic view of a prior art LED is illustrated. It is appreciated from the figure that a prior art LED 1 is connected to an aluminum supporter 11 by a conductive wire. The aluminum supporter 11 passes through a printed circuit board 12 and is welded to another surface of the printed circuit board 12 by tin 13. In the LED having such a structure, in the manufacturing process of the aluminum supporter 11, a shift from the center axis will cause a uniform illumination. This critical defect in this structure is that heat can not be dissipated easily. Since the operating temperature has a critical relation to the illumination. Therefore, the function of heat dissipation is used as an indication for determining the performance of an LED.
The way for calculating an LED operating temperature is:
1. Setting the speed of an electronic rectangular pulse wave to be 10 ms. PA1 2. Setting the conducting of a predetermined current to be 20 mA for lighting through 20 minutes continuously; PA1 3. For example, assume saturation voltage of an LED is 20 mA, the LED is lighted continuously for 30 minutes, then VF=1.92V, (2.1V-1.92V)=0.18V; PA1 4. 0.18V/2 mV=90.degree. C.; PA1 5. Total amount of heat: 90.degree. C./(20 mA.times.1.92V)=2343.degree.0 C./W; PA1 6. In the normal temperature, as the temperature reduces 10 degree C., the illumination of LED increases 9%; PA1 7. The concave cup of the present invention dissipate heat directly through the printed circuit board, and thus has a low contact heat resistance. Therefore, the advantages of a large transient large current, low heat dissipation, uniform illumination, high stability, low cost, mass production, etc. are achieved. Moreover, it can be done by workers themselves without needing to be performed externally. PA1 The first stage is about a concave cup printed circuit board, in which a printed circuit board is placed in a CNC computer driller, and a special milling cutter is used to drill a concave cup with a found flat bottom at the speed of 12000 to 25000 rps (the depth of the cup must be set). After drilling process is complete, a sand ejector serves to polish the interior of the concave cup. Then, plating with copper ions (which is similar to the penetrating process of guide holes in a general printed circuit board), after plating nickel step and plating metal step are completed, the first stage is finished. PA1 In the second stage, a manufacturing method of concave cup type LED is performed. The concave cup type LED in the first stage is processed through the steps of point gluing, fixing chip, baking, bonding, quality controlling, filling glue, baking again. Then a multiple usage concave cup type LED is fabricated.
A comparison of heat resistance about the concave cup type LED of the present invention and a LED of prior art are listed in the following:
heat resistance chip to supporter plus supporter to circuit board general LED 300.degree. C./W + 145.degree. C./W .apprxeq. 445.degree. C./W HP type I 155.degree. C./W + 145.degree. C./W .apprxeq. 300.degree. C./W HP type II 15.degree. C./W + 145.degree. C./W .apprxeq. 160.degree. C./W concave cup LED 0.degree. C./W + 15.degree. C./W .apprxeq. 15.degree. C./W
The printed circuit board of the present invention can control the arc angle. The technology of concave cup has achieved an international standard through the proofs of experiences, practical use and production and the lift test.
In the prior art, a concave cup is formed by punching a punching pin to compress a printed circuit board. Because the grass fiber of a printed circuit board can not completely avoid elastic fatigue, and because a concave cup formed by a punching pin will formed concave cups of different depths and an unstable elasticity, the illumination is not uniform and thus a low yield ratio is induced. Moreover, a concave cup formed by punching a punching pin to compress a printed circuit board has a flat oblique surface at the periphery thereof instead of round wall to be a reflecting surface, thus, the concave cup has an incorrect light guiding angle. Furthermore, a concave cup formed by punching a punching pin to compress a printed circuit board has a confined size within a range of smaller than 3.0 mm. Thus, the light reflecting distance and reflecting angle can not be used correctly. Therefore, light can not be mixed uniformly. Therefore, it can not be steadily used to the whole manufacturing method of a product.
Therefore, many disadvantages in the prior art is necessary to be improved, and a novel product is desired.